Patent application title: LIQUID CRYSTAL DISPLAY DEVICE

Abstract:

A liquid crystal display device includes a housing, a liquid crystal panel
provided in the housing and comprises first and second transparent
substrates spaced from each other at predetermined intervals, a sealing
member to seal an internal space formed between the first and second
transparent substrates, a liquid crystal to fill the internal space,
first and second transparent electrodes formed in the first and second
transparent substrates, respectively, and a polarizing plate to transmit
light in a predetermined polarizing direction, a backlight unit disposed
in the housing to emit surface light to the liquid crystal panel, and a
polarizing filter disposed in the housing, and spaced from the liquid
crystal panel at predetermined intervals to transmit predetermined
polarized light and to block other polarized light of incident light.

Claims:

1. A liquid crystal display device, comprising:a housing;a liquid crystal
panel provided in the housing and comprises first and second transparent
substrates spaced from each other at predetermined intervals, a sealing
member to seal an internal space formed between the first and second
transparent substrates, a liquid crystal to fill the internal space,
first and second transparent electrodes formed in the first and second
transparent substrates, respectively, and a first polarizing plate to
transmit light in a predetermined polarizing direction;a backlight unit
disposed in the housing to emit surface light to the liquid crystal
panel; anda polarizing filter disposed in the housing, and spaced from
the liquid crystal panel at predetermined intervals to transmit
predetermined polarized light and to block other polarized light of
incident light.

2. The liquid crystal display device according to claim 1, wherein the
first polarizing plate provided at an outside of the first transparent
substrate to face the backlight unit.

3. The liquid crystal display device according to claim 2, further
comprising:a second polarizing plate provided at a lateral side of the
second transparent substrate.

4. The liquid crystal display device according to claim 3, wherein the
polarizing filter and the second polarizing plate are arranged so that a
polarizing direction of light transmitting the polarizing filter is
substantially equal to that of light transmitting the second polarizing
plate.

5. The liquid crystal display device according to claim 1, further
comprising:an infrared filter provided at a lateral side of the
polarizing filter to block light in the infrared area among incident
light; andan ultraviolet filter provided at a lateral side of the
infrared filter to block light in the ultraviolet area among the incident
light.

6. The liquid crystal display device according to claim 5, further
comprising:a heat radiating member provided in the housing to cool the
liquid crystal panel and the polarizing filter.

7. The liquid crystal display device according to claim 6, wherein the
heating radiating member comprises:at least one fan provided in the
housing to introduce external air to the housing or to discharge internal
air of the housing to the outside.

8. The liquid crystal display device according to claim 7, wherein the fan
is provided in a lower rear side of the housing to introduce the external
air to a space between the liquid crystal panel and the polarizing
filter.

9. The liquid crystal display device according to claim 7, wherein the fan
is provided in an upper rear side of the housing to discharge air from
the housing to the outside.

10. The liquid crystal display device according to claim 6, wherein the
heat radiating member comprises:a heat absorber provided in the housing
to absorb heat; anda heat radiator provided outside of the housing to
discharge the heat absorbed by the heat absorber to the outside.

11. The liquid crystal display device according to claim 1, wherein a
distance between the liquid crystal panel and the polarizing filter
satisfies a following
formula.0.005.ltoreq.D/L≦0.1L=(H2+W2)1/2 Here, H
refers to a height of the liquid crystal panel, W is a width of the
liquid crystal panel, D is the distance D between the liquid crystal
panel and the polarizing filter, and L is a diagonal length of the liquid
crystal panel.

12. A liquid crystal display device, comprising:a liquid crystal panel;one
or more polarizing plates to transmit light in a predetermined polarized
direction and block other light; anda polarizing filter spaced from the
liquid crystal panel at one or more predetermined intervals, and to at
least one of reflect and absorb blocked light and to prevent the blocked
light from being directly applied to the liquid crystal display.

13. A liquid crystal display device, comprising:a liquid crystal panel to
display an image;a backlight unit to emit to emit surface light to the
liquid crystal panel;a polarizing filter spaced from the liquid crystal
panel at one or more predetermined intervals, and to transmit polarized
light and to block other polarized light of incident light;a housing to
enclose the liquid crystal panel, the backlight unit and the polarizing
filter; anda heat radiating member having a heat absorber to absorb heat
from an internal space inside the housing and a heat radiator to
discharge the absorbed heat outside the housing.

14. The liquid crystal display device according to claim 13, wherein the
heat absorber is disposed inside the housing and the heat radiator is
disposed outside the housing.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims priority under 35 U.S.C. §119(a) from
Korean Patent Application No. 10-2007-0127207, filed on Dec. 7, 2007 and
Korean Patent Application No. 10-2008-0047241, filed on May 21, 2008 in
the Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present general inventive concept relates to a liquid crystal
display device, and more particularly, to a liquid crystal display device
to be installed outdoors.

[0004]2. Description of the Related Art

[0005]Generally, a liquid crystal display (LCD) device is a type of a flat
panel display device, and includes a backlight unit emitting light and a
liquid crystal panel selectively transmitting light from the backlight
unit to form an image.

[0006]As liquid crystal panels have increased in size, demands and
application areas for an LCD device having the large-sized liquid crystal
panel have sharply increased.

[0007]If the LCD device is to be installed outdoors, the liquid crystal
panel may be exposed to sunlight having 1 kW/m2 radiant energy. In
this case, liquid crystals are heated by solar radiant energy, and may
not be driven normally. Thus, the successful outside installation of the
LCD device is, in reality, unlikely without a sun blocking structure.

[0008]FIG. 1 is a perspective view illustrating an LCD device which is
installed outdoors with a conventional light blocking plate.

[0009]As illustrated therein, the LCD device which can be installed
outdoors includes a liquid crystal panel 1, and a light blocking plate 5
disposed in front of the liquid crystal panel 1 to prevent direct rays of
light from being incident to the liquid crystal panel 1.

[0010]To block sunlight emitted from above and lateral sides, the light
blocking plate 5 includes an upper plate 6 provided on the liquid crystal
panel 1 and protruding forward, and left and right plates 7 and 8
provided at the left and right sides of the liquid crystal panel 1 and
protruding forward.

[0011]If the LCD device which can be installed outdoors includes the light
blocking plate 5 as described above, the direct rays of light is
prevented from being incident to the liquid crystal panel 1.

[0013]The present general inventive concept provides a LCD device to block
light not contributing to displaying images among solar radiant energy
incident to a liquid crystal panel, without an outwardly-protruding light
blocking plate, and to protect the liquid crystal panel from the solar
radiant energy.

[0014]Additional aspects and utilities of the present general inventive
concept will be set forth in part in the description which follows and,
in part, will be obvious from the description, or may be learned by
practice of the general inventive concept.

[0015]The foregoing and/or other aspects and utilities of the present
general inventive concept can be achieved by providing a liquid crystal
display device comprising a housing, a liquid crystal panel provided in
the housing and comprises first and second transparent substrates spaced
from each other at predetermined intervals, a sealing member to seal an
internal space formed between the first and second transparent
substrates, a liquid crystal to fill the internal space, first and second
transparent electrodes formed in the first and second transparent
substrates, respectively, and a first polarizing plate to transmit light
in a predetermined polarizing direction, a backlight unit disposed in the
housing to emit surface light to the liquid crystal panel, and a
polarizing filter disposed in the housing, and spaced from the liquid
crystal panel at predetermined intervals to transmit predetermined
polarized light and to block other polarized light of incident light.

[0016]The first polarizing plate may be provided at an outside of the
first transparent substrate to face the backlight unit.

[0017]The liquid crystal display device may further comprise a second
polarizing plate provided at a lateral side of the second transparent
substrate.

[0018]The polarizing filter and the second polarizing plate may be
arranged so that a polarizing direction of light transmitting the
polarizing filter is substantially equal to that of light transmitting
the second polarizing plate.

[0019]The liquid crystal display device may further comprise an infrared
filter provided at a lateral side of the polarizing filter to block light
in the infrared area among incident light, and an ultraviolet filter
provided at a lateral side of the infrared filter and to block light in
the ultraviolet area among the incident light.

[0020]The liquid crystal display device may further comprise a heat
radiating member provided in the housing to cool the liquid crystal panel
and the polarizing filter.

[0021]The heating radiating member may comprise at least one fan which is
provided in the housing to introduce external air to the housing or to
discharge internal air of the housing to the outside.

[0022]The fan may be provided in a lower rear side of the housing to
introduce the external air to a space between the liquid crystal panel
and the polarizing filter.

[0023]The fan may be provided in an upper rear side of the housing to
discharge air from the housing to the outside.

[0024]The heat radiating member may comprise a heat absorber provided in
the housing to absorb heat, and a heat radiator provided outside of the
housing to discharge the heat absorbed by the heat absorber to the
outside.

[0025]A distance between the liquid crystal panel and the polarizing
filter D may satisfy a following formula.

0.005≦D/L≦0.1

L=(H2+W2)1/2

[0026]Here, H refers to a height of the liquid crystal panel, W is a width
of the liquid crystal panel, D is the distance D between the liquid
crystal panel and the polarizing filter, and L is a diagonal length of
the liquid crystal panel.

[0027]The foregoing and/or other aspects and utilities of the present
general inventive concept can be achieved by providing a liquid crystal
display device including a liquid crystal panel, one or more polarizing
plates to transmit light in a predetermined polarized direction and block
other light, and a polarizing filter spaced from the liquid crystal panel
at one or more predetermined intervals, and to at least one of reflect
and absorb blocked light and to prevent the blocked light from being
directly applied to the liquid crystal display.

[0028]The foregoing and/or other aspects and utilities of the present
general inventive concept can be achieved by providing a liquid crystal
display device including a liquid crystal panel to display an image, a
backlight unit to emit to emit surface light to the liquid crystal panel,
a polarizing filter spaced from the liquid crystal panel at one or more
predetermined intervals, and to transmit polarized light and to block
other polarized light of incident light, a housing to enclose the liquid
crystal panel, the backlight unit and the polarizing filter, and a heat
radiating member having a heat absorber to absorb heat from an internal
space inside the housing and a heat radiator to discharge the absorbed
heat outside the housing.

[0029]The heat absorber may be disposed inside the housing and the heat
radiator may be disposed outside the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]The above and/or other aspects and utilities of the present general
inventive concept will become apparent and more readily appreciated from
the following description of the exemplary embodiments, taken in
conjunction with the accompanying drawings, in which:

[0031]FIG. 1 is a perspective view illustrating a LCD device which is
installed outdoors with a conventional light blocking plate;

[0032]FIG. 2 is a sectional view illustrating a LCD device according to an
exemplary embodiment of the present general inventive concept;

[0033]FIG. 3 illustrates a detailed configuration of a liquid crystal
panel in FIG. 2 and an external light blocking process of the LCD device
in FIG. 2;

[0034]FIG. 4 illustrates a size of the liquid crystal panel and a distance
between the liquid crystal panel and a polarizing filter; and

[0035]FIG. 5 is a sectional view of a LCD device according to another
exemplary embodiment of the present general inventive concept.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036]Reference will now be made in detail to embodiments of the present
general inventive concept, examples of which are illustrated in the
accompanying drawings, wherein like reference numerals refer to like
elements throughout. The embodiments are described below so as to explain
the present general inventive concept by referring to the figures.

[0037]FIG. 2 is a sectional view illustrating a LCD device according to an
exemplary embodiment of the present general inventive concept. FIG. 3
illustrates a detailed configuration of a liquid crystal panel in FIG. 2
and an external light blocking process of the LCD device in FIG. 2.

[0038]As illustrated therein, the LCD device according to the exemplary
embodiment of the present general inventive concept includes a housing
10, and a liquid crystal panel 20, a backlight unit 40 and a polarizing
filter 50 which are installed in the housing 10.

[0039]Referring to FIGS. 2 and 3, the liquid crystal panel 20 is a
non-emitter type display panel. The liquid crystal panel 20 selectively
transmits light emitted by the backlight unit 40 to each of a plurality
of pixels forming an image. The liquid crystal panel 20 includes first
and second transparent substrates 21 and 23, a sealing member 25, a
liquid crystal 26, first and second transparent electrodes 27 and 29 and
a polarizing plate 30.

[0040]The first and second transparent substrates 21 and 23 are spaced
from each other at predetermined intervals. The liquid crystal 26 is
injected between the first and second transparent substrates 21 and 23.
The sealing member 25 seals an internal space formed between the first
and second transparent substrates 21 and 23.

[0041]The first and second transparent electrodes 27 and 29 are
stripe-shaped electrodes formed in the first and second transparent
substrates 21 and 23, respectively. The first transparent electrode 27
intersects an alignment direction of the second transparent electrode 29.
A switching element (not illustrated) is provided at an intersection of
the first and second transparent electrodes 27 and 29 and controls power
supplied to the first and second transparent electrodes 27 and 29 to turn
on and off each pixel of the liquid crystal 26.

[0042]The polarizing plate 30 may include a first polarizing plate 31
provided in an external part of the first transparent substrate 21 and a
second polarizing plate 33 provided in an external part of the second
transparent substrate 23.

[0043]The first polarizing plate 31 transmits light in a predetermined
polarizing direction. That is, the first polarizing plate 31 transmits
specific polarized light emitted by the backlight unit 40 to the liquid
crystal 26 and blocks other polarized light. The light which has passed
through the first polarizing plate 31 progresses to the second polarizing
plate 33, with a polarizing direction determined for each pixel depending
on a driving status of the pixel.

[0044]The second polarizing plate 33 transmits light in a predetermined
polarizing direction and blocks other polarized light. Thus, the liquid
crystal panel 20 forms an image by blocking light which has passed
through some pixels and by transmitting light which has passed through
other pixels, corresponding to the driving status of the liquid crystal
26.

[0045]In this embodiment, the polarizing plate 30 includes the first
polarizing plate 33 and the second polarizing plate 33, but not limited
thereto. Alternatively, the polarizing filter 50 may perform an optical
function of the second polarizing plate 33 as described below. Thus, in
another embodiment, the second polarizing plate 33 may be removed.

[0046]The backlight unit 40 is installed in the housing 10, faces the
first polarizing plate 31 and emits surface light to the liquid crystal
panel 20.

[0047]According to the present embodiment, the backlight unit 40 is an
edge emitting type, and includes a light source 41 and a light guiding
plate 45 to guide a progress direction of the light emitted by the light
source 41. The light source 41 includes a lamp 43 and a reflection mirror
44 to reflect light emitted by the lamp 43 to the light guiding plate 45.
The light source 41 may include, for example, at least one light emitting
diode (LED) disposed at an edge of the light guiding plate 45. The
backlight unit 40 is not limited to the edge emitting type, and may
include a direct emitting type.

[0048]The polarizing filter 50 is spaced from the liquid crystal panel 20
at predetermined intervals, and transmits predetermined polarized light
of incident light and blocks other polarized light. Thus, if the LCD
device is installed outdoors, a portion of sunlight incident from the
outside is blocked. For example, in the present general inventive
concept, approximately 50%, for example, may be blocked. Thus, the liquid
crystal panel 20 is prevented from being thermal damaged by sunlight. As
the polarizing filter 50 is spaced from the liquid crystal panel 20,
light which is absorbed or reflected by the polarizing filter 50 to block
sunlight is not directly applied to the liquid crystal panel 20.

[0049]To transmit an image formed by the liquid crystal panel 20, the
polarizing filter 50 is disposed in consideration of the alignment
direction of the second polarizing plate 33. That is, the polarizing
filter 50 and the second polarizing plate 33 are arranged so that the
polarizing direction of the light transmitting the polarizing filter 50
is substantially equal to that of light transmitting the second
polarizing plate 33. As most of the image formed on the liquid crystal
panel 20 transmits through the polarizing film 50, a lowering of
brightness due to the polarizing filter 50 does not occur.

[0050]Here, the polarizing filter 50 transmits light polarized in a
predetermined direction therethrough and blocks other polarized light,
thereby serving as the second polarizing plate 33. Accordingly, the image
can be formed without the second polarizing plate 33.

[0051]The LCD device according to the exemplary embodiment of the present
general inventive concept may further include an infrared filter 61 and
an ultraviolet filter 65 which are provided in the housing 10.

[0052]The infrared filter 61 is provided in a lateral side of the
polarizing filter 50 and blocks light in the infrared area among incident
light. The ultraviolet filter 65 is provided in a lateral side of the
infrared filter 61 and blocks light in the ultraviolet area among the
incident light.

[0053]If the LCD device further includes the infrared filter 61 and the
ultraviolet filter 65, infrared rays (IR) and ultraviolet rays (UV)
included in the solar radiant energy, i.e., approximately 50% of the
solar radiant energy, is blocked.

[0054]Thus, about 50% of the incident solar radiant energy is blocked by
the infrared filter 61 and the ultraviolet filter 65, and another 50% of
the remaining solar radiant energy transmitting the infrared and
ultraviolet filters 61 and 65 is blocked by the polarizing filter 50. As
a result, only about 25% of the overall radiant energy passes through the
filters 61, 65 and 50 and is incident to the liquid crystal panel 20,
sharply reducing an impact of the solar radiant energy.

[0055]Even if the light blocking plate is not used, the liquid crystal 26
of the LCD device does not rise to a critical temperature.

[0056]The LCD device according to another embodiment may further include a
heat radiating member 70 to cool the liquid crystal panel 20 and the
polarizing filter 50.

[0057]The heat radiating member 70 may include at least one fan which is
provided in the housing 10.

[0058]FIG. 2 illustrates first and second fans 71 and 73 as an example of
the heat radiant member 70. Referring to FIG. 2, the first fan 71 is
provided in a lower rear side of the housing 10 to introduce external air
to a space 75 between the liquid crystal panel 20 and the polarizing
filter 50. The second fan 73 is provided in an upper rear side of the
housing 10 to discharge air from the housing 10 to the outside.

[0059]As described above, if the LCD device includes the first and second
fans 71 and 73 as the heat radiating member 70, air circulates in and
around the housing 10, and the liquid crystal panel 10 and the polarizing
filter 50 may be more efficiently cooled. Since impurities may be
introduced to the housing 10 when air circulates in and around the
housing 10, an air filter (not illustrated) may be provided in an opening
of the housing 10 having the first and second fans 71 and 73 to prevent
the impurities.

[0060]FIG. 4 illustrates a size of the liquid crystal panel 20 and a
distance between the liquid crystal panel 20 and the polarizing filter
50.

[0061]Referring to FIG. 4, a distance D between the liquid crystal panel
20 and the polarizing filter 50 can be determined, for example, in
consideration of a size of the liquid crystal panel 20. That is, if other
conditions are equal, a larger liquid crystal panel receives more solar
radiant energy. Then, the liquid crystal is very likely to be damaged.
Considering such circumstances, the distance D can satisfy a following
formula 1.

0.005≦D/L≦0.1

L=(H2+W2)1/2 [Formula 1]

[0062]Here, H refers to a height of the liquid crystal panel 20, W is a
width of the liquid crystal panel 20, D is the distance D between the
liquid crystal panel 20 and the polarizing filter 50, and L is a diagonal
length of the liquid crystal panel 20.

[0063]In the formula 1, a lowest value is a value where boundary layers of
air flow in the liquid crystal panel 20 and the polarizing filter 50 meet
each other when the liquid crystal panel 20 and the polarizing filter 50
are cooled by the first and second fans 71 and 73. If D/L is out of the
lowest value, air flow between the liquid crystal panel 20 and the
polarizing filter 50 is fully developed. Thus, a convective heat transfer
coefficient is drastically reduced.

[0064]In the formula 1, a highest value of D/L does not exist in the
thermal aspect. If D/L is out of the highest value of the formula 1, a
thickness of front and rear surfaces of the LCD device is very thick
compared to a screen size, creating limitations in an installing space.

[0065]FIG. 5 is a sectional view illustrating a LCD device according to
another exemplary embodiment of the present general inventive concept.

[0066]As illustrated therein, the LCD device according to the present
embodiment includes a housing 110, and a liquid crystal panel 20, a
backlight unit 40 and a polarizing filter 50 which are provided in the
housing 110. The LCD device may further include an infrared filter 61, an
ultraviolet filter 65 and a heat radiating member 170. The LCD device
according to the present embodiment is differentiated from that according
to the exemplary embodiment, illustrated in FIG. 2, in that the housing
110 is a closed configuration and a configuration of the heat radiating
member 170 is changed.

[0067]As the housing 110 is a closed configuration, air does not circulate
in and around the housing 110 unlike in the exemplary embodiment. Thus,
external impurities are not introduced to the housing 110 fundamentally.

[0068]The heat radiating member 170 is provided in and outside of the
housing 110. The heat radiating member 170 includes a heart absorber 171
which is provide in the housing 110 to absorb heat from an internal space
of the housing 110, and a heat radiator 173 which is provided out of the
housing 110 to discharge heat absorbed by the heat absorber 171 to the
outside. The heat absorbed by the heat absorber 171 is applied to the
heat radiator 173, and the heat radiator 173 discharges the heat to the
outside of the housing 110. Thus, the inside of the housing 110 may be
cooled.

[0069]FIG. 5 illustrates a heat sink having a plurality of heat radiating
fins as an example of the heat radiating member 170, but not limited
thereto. Alternatively, the heat radiating member 170 may include a heat
pipe. As a configuration and an operation of the heat pipe is known,
detailed description will be avoided.

[0070]As described above, the LCD device according to various embodiments
of the present general inventive concept includes an additional
polarizing filter spaced from a liquid crystal panel within a housing to
block other light than predetermined polarized light of incident light.
Thus, even if the LCD device is installed outside, direct emission of
solar radiant energy to the liquid crystal panel may be eased. Even if
installed outside, the liquid crystal panel of the LCD device may be
prevented from being overheated.

[0071]The LCD device according to various embodiments of the present
general inventive concept further includes an infrared filter and an
ultraviolet filter as well as the polarizing filter to block light in the
infrared area and the ultraviolet area included in solar radiant energy
to protect the liquid crystal panel from the solar radiant energy more
efficiently.

[0072]The LCD device according to various embodiments of the present
general inventive concept further includes a heat radiating member to
cool the liquid crystal panel and a polarizing filter in a housing. As
internal temperature of the housing is lowered, internal temperature of
the housing may be prevented from rising.

[0073]Since the LCD device according to various embodiments of the present
general inventive concept does not use a liquid blocking plate protruding
outwardly, a wide viewing angle may be secured and limitation of an
installing space may be reduced.

[0074]Although various exemplary embodiments of the present general
inventive concept have been illustrated and described, it will be
appreciated by those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
general inventive concept, the scope of which is defined in the appended
claims and their equivalents.